4.2.157. SPN 4356, FMI 3, DEF supply module heater relay low side open circuitΒΆ

Description

EEM4 monitoring system has detected open cicuit on DEF supply module heater relay low side.

Possible causes are:

  • The DEF supply module heater relay wiring is defective
  • The DEF supply module heater is defective

Reaction in EEM

The FC is stored and the warning lamp is activated. The CAN message indicates active fault.

NOTE: The present fault is classified as an emission related fault. Engine power will be reduced after a certain time defined by an authority.

Solution

First save the error log and then clear it. After clearing, restart the ECU. If the fault occurs again during the next driving cycle, check the following paths:

  • Check the DEF supply module heater relay wiring, the connectors and the contact surfaces of the connector pins (possible oxidation). (see Supply module)
  • Check the operation with another heater relay to see if the relay is defective.